Question

4x+4y=52 and -4x+2y=-28 the answer is x=12 and y=4????

Answer 1

4x+4(4)=52
4x+16=52
4x=52-16
4x=36
x=9

Answer 2

adding both the equations,
4x+4y= 52
-4x+2y=-28
------------
0+6y=24
=>y=24/6
=>y=3
put y=3 in any of the eqn.
for instance while putting in first eqn you get...
4x+4(3)=52
=>4x=52-12
=>4x=40
=>x=40/4
=>x=10
Inorder to verify your ans put both x and y value in any one of the equation and make sure that it satisfies as follows.
4(10)+4(3)=52
40+12=52
52=52
you can see both left hand side and right hand side are equal. hence satisfies
so the ans is x=10,y=3

Answer 3

y is actually 5

Answer 4

If the value of y is given then go for substituting it in the eqn,but you will get 2 different ans as shown,
4x+4(5)=52
=>4x=32
=>x=8
also,

-4x+2(5)=-28
=>-4x=-28+10
-4x=-18
=>x=18/4
If you're looking for a common soln for both eqn then it is x=10,y=3
Otherwise if you want solve for x for both the equation given the value of y as 5, you 2 different values of x